view mercurial/repair.py @ 48687:f8f2ecdde4b5

branchmap: skip obsolete revisions while computing heads

It's time to make this part of core Mercurial obsolescence-aware.

Not considering obsolete revisions when computing heads is clearly what
Mercurial should do. But there are a couple of small issues:

- Let's say tip of the repo is obsolete. There are two ways of finding tiprev
  for branchcache (both are in use): looking at input data for update() and
  looking at computed heads after update(). Previously, repo tip would be
  tiprev of the branchcache. With this patch, an obsolete revision can no
  longer be tiprev. And depending on what way we use for finding tiprev (input
  data vs computed heads) we'll get a different result. This is relevant when
  recomputing cache key from cache contents, and may lead to updating cache for
  obsolete revisions multiple times (not from scratch, because it still would
  be considered valid for a subset of revisions in the repo).

- If all commits on a branch are obsolete, the branchcache will include that
  branch, but the list of heads will be empty (that's why there's now `if not
  heads` when recomputing tiprev/tipnode from cache contents). Having an entry
  for every branch is currently required for notify extension (and
  test-notify.t to pass), because notify doesn't handle revsets in its
  subscription config very well and will throw an error if e.g. a branch
  doesn't exist.

- Cloning static HTTP repos may try to stat() a non-existent obsstore file. The
  issue is that we now care about obsolescence during clone, but statichttpvfs
  doesn't implement a stat method, so a regular vfs.stat() is used, and it
  assumes that file is local and calls os.stat().  During a clone, we're trying
  to stat() .hg/store/obsstore, but in static HTTP case we provide a literal
  URL to the obsstore file on the remote as if it were a local file path. On
  windows it actually results in a failure in test-static-http.t.

The first issue is going to be addressed in a series dedicated to making sure
branchcache is properly and timely written on disk (it wasn't perfect even
before this patch, but there aren't enough tests to demonstrate that). The
second issue will be addressed in a future patch for notify extension that will
make it not raise an exception if a branch doesn't exist. And the third one was
partially addressed in the previous patch in this series and will be properly
fixed in a future patch when this series is accepted.

filteredhash() grows a keyword argument to make sure that branchcache is also
invalidated when there are new obsolete revisions in its repo view. This way
the on-disk cache format is unchanged and compatible between versions (although
it will obviously be recomputed when switching versions before/after this patch
and the repo has obsolete revisions).

There's one test that uses plain `hg up` without arguments while updated to a
pruned commit. To make this test pass, simply return current working directory
parent. Later in this series this code will be replaced by what prune command
does: updating to the closest non-obsolete ancestor.

Test changes:

test-branch-change.t: update branch head and cache update message. The head of
default listed in hg heads is changed because revision 2 was rewritten as 7,
and 1 is the closest ancestor on the same branch, so it's the head of default
now.

The cache invalidation message appears now because of the cache hash change,
since we're now accounting for obsolete revisions. Here's some context:

"served.hidden" repo filter means everything is visible (no filtered
revisions), so before this series branch2-served.hidden file would not contain
any cache hash, only revnum and node. Now it also has a hash when there are
obsolete changesets in the repo. The command that the message appears for is
changing branch of 5 and 6, which are now obsolete, so the cache hash changes.

In general, when cache is simply out-of-date, it can be updated using the old
version as a base. But if cache hash differs, then the cache for that
particular repo filter is recomputed (at least with the current
implementation). This is what happens here.

test-obsmarker-template.t: the pull reports 2 heads changed, but after that the
repo correctly sees only 1. The new message could be better, but it's still an
improvement over the previous one where hg pull suggested merging with an
obsolete revision.

test-obsolete.t: we can see these revisions in hg log --hidden, but they
shouldn't be considered heads even with --hidden.

test-rebase-obsolete{,2}.t: there were new heads created previously after
making new orphan changesets, but they weren't detected. Now we are properly
detecting and reporting them.

test-rebase-obsolete4.t: there's only one head now because the other head is
pruned and was falsely reported before.

test-static-http.t: add obsstore to the list of requested files. This file
doesn't exist on the remotes, but clients want it anyway (they get 404). This
is fine, because there are other nonexistent files that clients request, like
.hg/bookmarks or .hg/cache/tags2-served.

Differential Revision: https://phab.mercurial-scm.org/D12097

# repair.py - functions for repository repair for mercurial
#
# Copyright 2005, 2006 Chris Mason <[e-mail]>
# Copyright 2007 Olivia Mackall
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import errno

from .i18n import _
from .node import (
    hex,
    short,
)
from . import (
    bundle2,
    changegroup,
    discovery,
    error,
    exchange,
    obsolete,
    obsutil,
    pathutil,
    phases,
    pycompat,
    requirements,
    scmutil,
    util,
)
from .utils import (
    hashutil,
    stringutil,
    urlutil,
)


def backupbundle(
    repo, bases, heads, node, suffix, compress=True, obsolescence=True
):
    """create a bundle with the specified revisions as a backup"""

    backupdir = b"strip-backup"
    vfs = repo.vfs
    if not vfs.isdir(backupdir):
        vfs.mkdir(backupdir)

    # Include a hash of all the nodes in the filename for uniqueness
    allcommits = repo.set(b'%ln::%ln', bases, heads)
    allhashes = sorted(c.hex() for c in allcommits)
    totalhash = hashutil.sha1(b''.join(allhashes)).digest()
    name = b"%s/%s-%s-%s.hg" % (
        backupdir,
        short(node),
        hex(totalhash[:4]),
        suffix,
    )

    cgversion = changegroup.localversion(repo)
    comp = None
    if cgversion != b'01':
        bundletype = b"HG20"
        if compress:
            comp = b'BZ'
    elif compress:
        bundletype = b"HG10BZ"
    else:
        bundletype = b"HG10UN"

    outgoing = discovery.outgoing(repo, missingroots=bases, ancestorsof=heads)
    contentopts = {
        b'cg.version': cgversion,
        b'obsolescence': obsolescence,
        b'phases': True,
    }
    return bundle2.writenewbundle(
        repo.ui,
        repo,
        b'strip',
        name,
        bundletype,
        outgoing,
        contentopts,
        vfs,
        compression=comp,
    )


def _collectfiles(repo, striprev):
    """find out the filelogs affected by the strip"""
    files = set()

    for x in pycompat.xrange(striprev, len(repo)):
        files.update(repo[x].files())

    return sorted(files)


def _collectrevlog(revlog, striprev):
    _, brokenset = revlog.getstrippoint(striprev)
    return [revlog.linkrev(r) for r in brokenset]


def _collectbrokencsets(repo, files, striprev):
    """return the changesets which will be broken by the truncation"""
    s = set()

    for revlog in manifestrevlogs(repo):
        s.update(_collectrevlog(revlog, striprev))
    for fname in files:
        s.update(_collectrevlog(repo.file(fname), striprev))

    return s


def strip(ui, repo, nodelist, backup=True, topic=b'backup'):
    # This function requires the caller to lock the repo, but it operates
    # within a transaction of its own, and thus requires there to be no current
    # transaction when it is called.
    if repo.currenttransaction() is not None:
        raise error.ProgrammingError(b'cannot strip from inside a transaction')

    # Simple way to maintain backwards compatibility for this
    # argument.
    if backup in [b'none', b'strip']:
        backup = False

    repo = repo.unfiltered()
    repo.destroying()
    vfs = repo.vfs
    # load bookmark before changelog to avoid side effect from outdated
    # changelog (see repo._refreshchangelog)
    repo._bookmarks
    cl = repo.changelog

    # TODO handle undo of merge sets
    if isinstance(nodelist, bytes):
        nodelist = [nodelist]
    striplist = [cl.rev(node) for node in nodelist]
    striprev = min(striplist)

    files = _collectfiles(repo, striprev)
    saverevs = _collectbrokencsets(repo, files, striprev)

    # Some revisions with rev > striprev may not be descendants of striprev.
    # We have to find these revisions and put them in a bundle, so that
    # we can restore them after the truncations.
    # To create the bundle we use repo.changegroupsubset which requires
    # the list of heads and bases of the set of interesting revisions.
    # (head = revision in the set that has no descendant in the set;
    #  base = revision in the set that has no ancestor in the set)
    tostrip = set(striplist)
    saveheads = set(saverevs)
    for r in cl.revs(start=striprev + 1):
        if any(p in tostrip for p in cl.parentrevs(r)):
            tostrip.add(r)

        if r not in tostrip:
            saverevs.add(r)
            saveheads.difference_update(cl.parentrevs(r))
            saveheads.add(r)
    saveheads = [cl.node(r) for r in saveheads]

    # compute base nodes
    if saverevs:
        descendants = set(cl.descendants(saverevs))
        saverevs.difference_update(descendants)
    savebases = [cl.node(r) for r in saverevs]
    stripbases = [cl.node(r) for r in tostrip]

    stripobsidx = obsmarkers = ()
    if repo.ui.configbool(b'devel', b'strip-obsmarkers'):
        obsmarkers = obsutil.exclusivemarkers(repo, stripbases)
    if obsmarkers:
        stripobsidx = [
            i for i, m in enumerate(repo.obsstore) if m in obsmarkers
        ]

    newbmtarget, updatebm = _bookmarkmovements(repo, tostrip)

    backupfile = None
    node = nodelist[-1]
    if backup:
        backupfile = _createstripbackup(repo, stripbases, node, topic)
    # create a changegroup for all the branches we need to keep
    tmpbundlefile = None
    if saveheads:
        # do not compress temporary bundle if we remove it from disk later
        #
        # We do not include obsolescence, it might re-introduce prune markers
        # we are trying to strip.  This is harmless since the stripped markers
        # are already backed up and we did not touched the markers for the
        # saved changesets.
        tmpbundlefile = backupbundle(
            repo,
            savebases,
            saveheads,
            node,
            b'temp',
            compress=False,
            obsolescence=False,
        )

    with ui.uninterruptible():
        try:
            with repo.transaction(b"strip") as tr:
                # TODO this code violates the interface abstraction of the
                # transaction and makes assumptions that file storage is
                # using append-only files. We'll need some kind of storage
                # API to handle stripping for us.
                oldfiles = set(tr._offsetmap.keys())
                oldfiles.update(tr._newfiles)

                tr.startgroup()
                cl.strip(striprev, tr)
                stripmanifest(repo, striprev, tr, files)

                for fn in files:
                    repo.file(fn).strip(striprev, tr)
                tr.endgroup()

                entries = tr.readjournal()

                for file, troffset in entries:
                    if file in oldfiles:
                        continue
                    with repo.svfs(file, b'a', checkambig=True) as fp:
                        fp.truncate(troffset)
                    if troffset == 0:
                        repo.store.markremoved(file)

                deleteobsmarkers(repo.obsstore, stripobsidx)
                del repo.obsstore
                repo.invalidatevolatilesets()
                repo._phasecache.filterunknown(repo)

            if tmpbundlefile:
                ui.note(_(b"adding branch\n"))
                f = vfs.open(tmpbundlefile, b"rb")
                gen = exchange.readbundle(ui, f, tmpbundlefile, vfs)
                # silence internal shuffling chatter
                maybe_silent = (
                    repo.ui.silent()
                    if not repo.ui.verbose
                    else util.nullcontextmanager()
                )
                with maybe_silent:
                    tmpbundleurl = b'bundle:' + vfs.join(tmpbundlefile)
                    txnname = b'strip'
                    if not isinstance(gen, bundle2.unbundle20):
                        txnname = b"strip\n%s" % urlutil.hidepassword(
                            tmpbundleurl
                        )
                    with repo.transaction(txnname) as tr:
                        bundle2.applybundle(
                            repo, gen, tr, source=b'strip', url=tmpbundleurl
                        )
                f.close()

            with repo.transaction(b'repair') as tr:
                bmchanges = [(m, repo[newbmtarget].node()) for m in updatebm]
                repo._bookmarks.applychanges(repo, tr, bmchanges)

            # remove undo files
            for undovfs, undofile in repo.undofiles():
                try:
                    undovfs.unlink(undofile)
                except OSError as e:
                    if e.errno != errno.ENOENT:
                        ui.warn(
                            _(b'error removing %s: %s\n')
                            % (
                                undovfs.join(undofile),
                                stringutil.forcebytestr(e),
                            )
                        )

        except:  # re-raises
            if backupfile:
                ui.warn(
                    _(b"strip failed, backup bundle stored in '%s'\n")
                    % vfs.join(backupfile)
                )
            if tmpbundlefile:
                ui.warn(
                    _(b"strip failed, unrecovered changes stored in '%s'\n")
                    % vfs.join(tmpbundlefile)
                )
                ui.warn(
                    _(
                        b"(fix the problem, then recover the changesets with "
                        b"\"hg unbundle '%s'\")\n"
                    )
                    % vfs.join(tmpbundlefile)
                )
            raise
        else:
            if tmpbundlefile:
                # Remove temporary bundle only if there were no exceptions
                vfs.unlink(tmpbundlefile)

    repo.destroyed()
    # return the backup file path (or None if 'backup' was False) so
    # extensions can use it
    return backupfile


def softstrip(ui, repo, nodelist, backup=True, topic=b'backup'):
    """perform a "soft" strip using the archived phase"""
    tostrip = [c.node() for c in repo.set(b'sort(%ln::)', nodelist)]
    if not tostrip:
        return None

    backupfile = None
    if backup:
        node = tostrip[0]
        backupfile = _createstripbackup(repo, tostrip, node, topic)

    newbmtarget, updatebm = _bookmarkmovements(repo, tostrip)
    with repo.transaction(b'strip') as tr:
        phases.retractboundary(repo, tr, phases.archived, tostrip)
        bmchanges = [(m, repo[newbmtarget].node()) for m in updatebm]
        repo._bookmarks.applychanges(repo, tr, bmchanges)
    return backupfile


def _bookmarkmovements(repo, tostrip):
    # compute necessary bookmark movement
    bm = repo._bookmarks
    updatebm = []
    for m in bm:
        rev = repo[bm[m]].rev()
        if rev in tostrip:
            updatebm.append(m)
    newbmtarget = None
    # If we need to move bookmarks, compute bookmark
    # targets. Otherwise we can skip doing this logic.
    if updatebm:
        # For a set s, max(parents(s) - s) is the same as max(heads(::s - s)),
        # but is much faster
        newbmtarget = repo.revs(b'max(parents(%ld) - (%ld))', tostrip, tostrip)
        if newbmtarget:
            newbmtarget = repo[newbmtarget.first()].node()
        else:
            newbmtarget = b'.'
    return newbmtarget, updatebm


def _createstripbackup(repo, stripbases, node, topic):
    # backup the changeset we are about to strip
    vfs = repo.vfs
    cl = repo.changelog
    backupfile = backupbundle(repo, stripbases, cl.heads(), node, topic)
    repo.ui.status(_(b"saved backup bundle to %s\n") % vfs.join(backupfile))
    repo.ui.log(
        b"backupbundle", b"saved backup bundle to %s\n", vfs.join(backupfile)
    )
    return backupfile


def safestriproots(ui, repo, nodes):
    """return list of roots of nodes where descendants are covered by nodes"""
    torev = repo.unfiltered().changelog.rev
    revs = {torev(n) for n in nodes}
    # tostrip = wanted - unsafe = wanted - ancestors(orphaned)
    # orphaned = affected - wanted
    # affected = descendants(roots(wanted))
    # wanted = revs
    revset = b'%ld - ( ::( (roots(%ld):: and not _phase(%s)) -%ld) )'
    tostrip = set(repo.revs(revset, revs, revs, phases.internal, revs))
    notstrip = revs - tostrip
    if notstrip:
        nodestr = b', '.join(sorted(short(repo[n].node()) for n in notstrip))
        ui.warn(
            _(b'warning: orphaned descendants detected, not stripping %s\n')
            % nodestr
        )
    return [c.node() for c in repo.set(b'roots(%ld)', tostrip)]


class stripcallback(object):
    """used as a transaction postclose callback"""

    def __init__(self, ui, repo, backup, topic):
        self.ui = ui
        self.repo = repo
        self.backup = backup
        self.topic = topic or b'backup'
        self.nodelist = []

    def addnodes(self, nodes):
        self.nodelist.extend(nodes)

    def __call__(self, tr):
        roots = safestriproots(self.ui, self.repo, self.nodelist)
        if roots:
            strip(self.ui, self.repo, roots, self.backup, self.topic)


def delayedstrip(ui, repo, nodelist, topic=None, backup=True):
    """like strip, but works inside transaction and won't strip irreverent revs

    nodelist must explicitly contain all descendants. Otherwise a warning will
    be printed that some nodes are not stripped.

    Will do a backup if `backup` is True. The last non-None "topic" will be
    used as the backup topic name. The default backup topic name is "backup".
    """
    tr = repo.currenttransaction()
    if not tr:
        nodes = safestriproots(ui, repo, nodelist)
        return strip(ui, repo, nodes, backup=backup, topic=topic)
    # transaction postclose callbacks are called in alphabet order.
    # use '\xff' as prefix so we are likely to be called last.
    callback = tr.getpostclose(b'\xffstrip')
    if callback is None:
        callback = stripcallback(ui, repo, backup=backup, topic=topic)
        tr.addpostclose(b'\xffstrip', callback)
    if topic:
        callback.topic = topic
    callback.addnodes(nodelist)


def stripmanifest(repo, striprev, tr, files):
    for revlog in manifestrevlogs(repo):
        revlog.strip(striprev, tr)


def manifestrevlogs(repo):
    yield repo.manifestlog.getstorage(b'')
    if scmutil.istreemanifest(repo):
        # This logic is safe if treemanifest isn't enabled, but also
        # pointless, so we skip it if treemanifest isn't enabled.
        for t, unencoded, size in repo.store.datafiles():
            if unencoded.startswith(b'meta/') and unencoded.endswith(
                b'00manifest.i'
            ):
                dir = unencoded[5:-12]
                yield repo.manifestlog.getstorage(dir)


def rebuildfncache(ui, repo, only_data=False):
    """Rebuilds the fncache file from repo history.

    Missing entries will be added. Extra entries will be removed.
    """
    repo = repo.unfiltered()

    if requirements.FNCACHE_REQUIREMENT not in repo.requirements:
        ui.warn(
            _(
                b'(not rebuilding fncache because repository does not '
                b'support fncache)\n'
            )
        )
        return

    with repo.lock():
        fnc = repo.store.fncache
        fnc.ensureloaded(warn=ui.warn)

        oldentries = set(fnc.entries)
        newentries = set()
        seenfiles = set()

        if only_data:
            # Trust the listing of .i from the fncache, but not the .d. This is
            # much faster, because we only need to stat every possible .d files,
            # instead of reading the full changelog
            for f in fnc:
                if f[:5] == b'data/' and f[-2:] == b'.i':
                    seenfiles.add(f[5:-2])
                    newentries.add(f)
                    dataf = f[:-2] + b'.d'
                    if repo.store._exists(dataf):
                        newentries.add(dataf)
        else:
            progress = ui.makeprogress(
                _(b'rebuilding'), unit=_(b'changesets'), total=len(repo)
            )
            for rev in repo:
                progress.update(rev)

                ctx = repo[rev]
                for f in ctx.files():
                    # This is to minimize I/O.
                    if f in seenfiles:
                        continue
                    seenfiles.add(f)

                    i = b'data/%s.i' % f
                    d = b'data/%s.d' % f

                    if repo.store._exists(i):
                        newentries.add(i)
                    if repo.store._exists(d):
                        newentries.add(d)

            progress.complete()

        if requirements.TREEMANIFEST_REQUIREMENT in repo.requirements:
            # This logic is safe if treemanifest isn't enabled, but also
            # pointless, so we skip it if treemanifest isn't enabled.
            for dir in pathutil.dirs(seenfiles):
                i = b'meta/%s/00manifest.i' % dir
                d = b'meta/%s/00manifest.d' % dir

                if repo.store._exists(i):
                    newentries.add(i)
                if repo.store._exists(d):
                    newentries.add(d)

        addcount = len(newentries - oldentries)
        removecount = len(oldentries - newentries)
        for p in sorted(oldentries - newentries):
            ui.write(_(b'removing %s\n') % p)
        for p in sorted(newentries - oldentries):
            ui.write(_(b'adding %s\n') % p)

        if addcount or removecount:
            ui.write(
                _(b'%d items added, %d removed from fncache\n')
                % (addcount, removecount)
            )
            fnc.entries = newentries
            fnc._dirty = True

            with repo.transaction(b'fncache') as tr:
                fnc.write(tr)
        else:
            ui.write(_(b'fncache already up to date\n'))


def deleteobsmarkers(obsstore, indices):
    """Delete some obsmarkers from obsstore and return how many were deleted

    'indices' is a list of ints which are the indices
    of the markers to be deleted.

    Every invocation of this function completely rewrites the obsstore file,
    skipping the markers we want to be removed. The new temporary file is
    created, remaining markers are written there and on .close() this file
    gets atomically renamed to obsstore, thus guaranteeing consistency."""
    if not indices:
        # we don't want to rewrite the obsstore with the same content
        return

    left = []
    current = obsstore._all
    n = 0
    for i, m in enumerate(current):
        if i in indices:
            n += 1
            continue
        left.append(m)

    newobsstorefile = obsstore.svfs(b'obsstore', b'w', atomictemp=True)
    for bytes in obsolete.encodemarkers(left, True, obsstore._version):
        newobsstorefile.write(bytes)
    newobsstorefile.close()
    return n